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1a: STATES OF MATTER


1.1 Understand the arrangement, movement and energy of the particles in each of the three states of matter: solid, liquid and gas
1.2 Describe how the interconversion of solids, liquids and gases are achieved and recall the names used for these interconversions
1.3 Describe the changes in arrangement, movement and energy of particles during these interconversions

The Kinetic Particle Theory
The main ideas of the kinetic theory are (this is your factual knowledge)
  • All the matter consists of tiny particles; these particles can be atoms, molecules or ions.
  • All particular move and, therefore, have kinetic energy; they vibrate or move position or both
  • There are forces between the particles
  • When matter is heated its particles gain more kinetic energy and move faster or vibrate more
  • When matter is heated it expands as its particles move further apart
  • The temperature of a substance tells us the average amount of kinetic energy of all its particles

The Three States of Matter
We can use the kinetic theory to describe the three states of matter.

State

Forces of Attraction Between Particles

Energy of particles

Arrangement of particles

Movement/motion of particles

SOLID

Strong Forces
Little Energy
  • Particles are held in fixed positions making an ordered arrangement or lattice
  • Particles are close together
  • When heated they move slightly further apart form each other
  • Particles vibrate around a point
  • Particles cannot move from their positions
  • When heated they vibrate more and move further apart a little (expansion)

LIQUID

Forces of attraction have less effect so that particles still stick together
Moderate Energy
  • Particles are in a random/irregular arrangement
  • Particles are still fairly close together
  • When heated they move slightly further apart from each other
  • Particles can move past one another and move randomly
  • When heated they move faster and move further apart a little (expansion)

GAS

Forces of attraction have no effect - almost no forces holding them together
A lot of energy
  • Random arrangement
  • Particles are very far apart/a lot of space between them/large distance between them
  • When heated they move even further apart
  • Particles move randomly (each particle in its own direction) and very fast
  • Particles move freely, constantly and in straight lines
  • Particles bounce off the walls of the containers causing pressure
  • When heated the particles move faster and move much further apart (a lot of expansion)

Lets now use these ideas to explain the differences in physical properties between the three states of matter (application of knowledge)


OBSERVATIONS

EXPLANATION

SOLID
Solids have fixed shape and volume (volume depends on number of particles + space between them)
The particles are in a fixed position

Solids cannot be compressed
Solid atoms are already tight enough

Solids only expand a little when heated
Forces of attraction are too strong
LIQUID
Liquids have a fixed volume
Particles are quite close and attracted strength

Liquids do not have a fixed shape (depends on the position of the particles)
Particles can move past one another

Liquids can flow
Particles move rapidly and passes another particle
GAS
Gases do not have a fixed shape or volume
Gas particles can move freely

Gas can easily be compressed
They have large space between each particles

Gas always fill up available space
Particles can move freely

Changes in State of Matter
The heating graph below shows what happens to the state and temperature of a solid substance when it is heated.
State_of_matter.jpg
The point where solid starts to become liquid is the melting point.
The point where liquid starts to become gas is the boiling point.

When a substance is heated its particles take in energy and use the energy to increase their movement and move further apart/ PARTICLES OR MOLECULES DO NOT GET BIGGER (OR SMALLER) when they are heated (or cooled).

Melting
When a solid is heated its particles gain energy and move faster. Eventually they gain enough energy to move away their positions and begin to vibrate around each other. The solid melts to form a liquid. The temperature at which solid melts is the melting point. The temperature at which a solid melts tells us how strongly its particles are held together. Substances with high melting points have strong forces of attraction between their particles. Substances with low melting points have weak forces between their particles.

Boiling
When a liquid is heated the particles gain energy and move around faster and faster. Some particles near the surface of the liquid have enough energy to escape into air and form vapor. This process is called evaporation. Eventually a temperature is reached at which the particles from the liquid surface so rapidly that bubbles of vapor (liquid) are formed.


Cooling Graphs (Energy is given out)
Cooling.gif
During the cooling, the particles lose energy, come closer together and when they collide, they stick together to form droplets forming a liquid
If cooled further in the liquid state, they eventually move so slowly that start vibrating around a point.
During condensing and freezing the particles lose energy as they need less energy because they slow down and come closer together again. The forces between the particles have a much greater effect.

Changes of State
Changes_of_State.jpg